Omega-3 fatty acids, also called n-3 poly unsaturated fatty acids (“PUPA”), have long been known to have beneficial effects in humans, particularly with regard to reducing the risk of coronary heart disease, reducing obesity, improving diabetic parameters including blood glucose levels, and improving other parameters relevant to metabolic syndrome. These fatty acids have a number of beneficial effects, among which is lowering elevated blood triglyceride levels down to more clinically acceptable values (Harris et. al., Atherosclerosis (2008); 197(1): 12-24). Omega-3 fatty acids can also assist in weight/fat loss in overweight individuals. Omega-3 fatty acids are typically isolated from marine sources, such as fish oil.
According to the World Health Organization, evidence is “convincing” that consumption of palmitic acid increases the risk of developing cardiovascular diseases, placing it in the same evidence category as trans fatty acids; dietary intake of palmitate and oleate has a broad impact on systemic and tissue lipid profiles in humans.” Palmitate raises “bad cholesterol” known as LDL, i.e., low density lipoprotein. Palmitic acid is prepared by treating fats and oils with water at a high pressure and temperature (above 200° C., or 390° F.), leading to the hydrolysis of triglycerides. The resulting mixture is then distilled. Palmitic acid is mainly used to produce soaps, cosmetics, and release agents.
Palmitoleic acid, or(Z)-9-hexadecenoic acid, is an Omega-7 monounsaturated fatty acid that is a common constituent of the glycerides found in human tissue. It is present in all tissues but, in general, found in higher concentrations in the liver. Palmitoleate was shown to possibly influence fatty liver deposition/production, insulin action, palmitate, and fatty acid synthase, leading to the proposal of a new term, “lipokine,” having hormone-like effects. As a beneficial fatty acid, it has been shown to increase insulin sensitivity by suppressing inflammation, as well as to inhibit the destruction of insulin-secreting pancreatic beta cells and may have a role in addressing obesity. Palmitoleic acid and derivatives are used in nutritional supplements. Therefore it is of high importance to produce high purity palmitoleic acid and derivatives for such use.
Menhaden oil contains about 30% of Omega-3 fatty acids, which have multiple health benefits. The remaining 70% of oil are non-Omega-3 fatty acids. As the demand for Omega-3 concentrates continues to increase, the manufacturing process generates an increasing quantity of co-products. These co-products are frequently low in Omega-3 fatty acids, but contain other valuable fatty acids, such as palmitoleic acid (POA).
Refined fish oil consists of various fatty acids in triglyceride form, i.e., glycerol backbone with three different fatty acids attached to it. To achieve a meaningful fractionation of fatty acids, triglycerides are often esterified into fatty acid ethyl esters (FAEEs), where each fatty acid is attached to ethanol. Then, FAEEs are passed through a fractional distillation column, which separates the FAEEs by molecular weight. Because of the structural similarity of many fatty acids of nutritional and pharmacological relevance, their purification or the enrichment of a mixture of fatty acids to a desired fatty acid is a challenging process. A convenient and inexpensive method of enriching POA or its derivatives would represent a significant advance in the art. Surprisingly, the present invention provides such a method.
Fats containing palmitoleic acid (C16:1 fatty acid) are known. In fact palmitoleic acid is a component in natural oils such as oils derived from macadamia nuts, which can contain up to 27% of C16:1 fatty acid. Other oils like fish oil or seal blubber contain appreciable amounts of C16:1 fatty acid. Palmitoleic acid is considered to be a healthy oil component, with health benefits such as antitumor activity (JP 59062523, Toyo Jozo Co Ltd), lowering serum cholesterol and LDL (Food Australia 1996, pp 216-222), and protective effects against ventricular arrhythmias as disclosed in U.S. Pat. No. 5,198,250. However, the known fats containing appreciable amounts of C16:1 also contain high amounts of other fatty acids such as C16:0 and C18:1. It would be very beneficial to produce fins that combine high levels of C16:1 with relatively low levels of C16:0. This would improve the performance, such as opacity, purability, viscosity, dosing, and blending of these fats considerably. An attempt to achieve this is disclosed in JP-laid open 01/187 089 (Shikibo Ltd).
One of the known processes to fractionate mixtures of fatty acid is the separation using urea (U.S. Pat. No. 5,078,920). This method separates relatively saturated species based upon that mixture of straight chain polar organic compounds into fractions respectively richer and poorer of unsaturated material. The more saturated components are complexed with urea to form a clathrate compound.
Another process used for fractionation especially used to increase the ratio of palmitoleic acid compared to palmitic acid is described in U.S. Pat. No. 6,461,662; this process involves a partial enzymatic hydrolysis of material derived from fish oil using an enzyme with specificity for palmitoleic acid and its derivatives, removal of the fatty acid followed by (i) dry fractionation or (ii) wet fractionation. This method is undesirable because it uses of a large amount of solvent.
Because of the structural similarity of many fatty acids of nutritional and pharmacological relevance, their purification or the enrichment of a mixture of fatty acids to a desired fatty acid is a challenging process. What is needed in the art is a convenient, resource- and cost-efficient method to produce oil mixtures that are enriched in palmitoleic acid. Surprisingly, the present invention provides such a method.